Cylinders of two-cycle motors



March 6, 1956 P. L. TORRE 2,737,171

CYLINDERS OF TWO-CYCLE MOTORS Filed Nov. 15, 1952 IN VEN TOR. l P/E L (//G/ TOZE' A Trag/VWS United States Patent O CYLINDERS F TWO-CYCLE MOTORS Pier Luigi Torre, Milan, Italy Application November 13, 1952, Serial No. 320,171

1 Claim. (Cl. 12S- 193) The present invention relates to two-cycle motors and more particularly cylinders of two-cycle motors of the type cast in aluminium alloy or the like, on a steel or cast-iron tube.

It is a known practice to employ, for two stroke motors, cylinders formed by a cast iron or steel liner, onto which, by a known process, a light alloy is cast after a special preparation of the liners surface, s0 as to create a true and proper transition alloy between the aluminium and the liner, this being very efficacious for a good heat transmission.

The exhaust, inlet and scavenging conduits are provided in the aluminium part also carrying the cooling fins. v

Such a solution possesses substantial cost and weight advantages; however, nothwithstanding the good thermic conductivity of aluminium assisting in the carrying away of heat, it has been noticed that with such cylinders the power developed by the motors using cylinders completely cast of cast iron, cannot be attained. Experience also shows that the entire cylinder body attains an appreciably higher temperature than does the cast iron one, dependently from the high heat tlow that traversing the exhaust conduit propagates itself to the cylinder mass.

The solution forming an object of the present invention aims to hinder said heat ow that detrimentallyaffects the lilling coetiicient of the cylinder and therefore the power of the motor.

The accompanying drawing shows schematically and by way of example two ways for practically realising the invention and specifically:

Figures 1 and 2 respectively represent a vertical and a horizontal section of a half a cylinder with its exhaust conduit provided with the improvement according to the present invention;

Figures 3 and 4 are two sections analogous to the preceding ones, of another form of embodiment of the invention.

As results from Figures 1 and 2, the cylinder comprises a liner 1, made of cast iron or of steel, onto which a light alloy, ncarrying envelope 2 'is cast, said envelope also comprising the exhaust conduit 3. According to the present invention, said exhaust conduit is lined, in the case illustrated, for the part coming into contact with the exhaust gases, with a metal sheet jacket 4 made of a heat resisting material, and perfectly matching the inside shape of conduit 3. Said jacket can either be simply inserted into conduit 3 or it may be inserted during the casting operation, in which case, however, it is necessary to so prepare the surface of said metal sheet jacket that the aluminium casting 3 does not take a hold on it. The reason is that in case such a hold should take place a perfect transmission of heat would be had from jacket 4 to the aluminium, whereas it is desired that said transmission be vthe smallest possible in order to prevent the propagation of heat to the, mass of the cylinder.

According to the embodiment illustrated in Figures 3 and 4, we still have a liner 1 coated with a body of cast aluminium 2, with fins for dispersing the heat. In this case, the exhaust conduit 3 is lined with a metal sheet 4, so disposed, however, as to leave between the aluminium casting 3 and sheet 4 an air space, and this to the end of still more hindering the heat ow. Said air space 5 can be obtained in a simple manner by means of two projections 6 and 7 provided on the metal sheet at the two ends of it, respectively.

It is evident from the preceding description that the improvement being the object of the invention is simple as to realisation, economical as to cost and such as to assure remarkable working advantages to the motor.

Of course, the dimensions and the material constituting the sheet metal lining of the exhaust conduit, its manner of application and the whole of the constructional details, may vary without, however, going out for this reason from the leld of the present invention.

What I claim is:

In an internal combustion engine, a cylinder comprising a liner, a reinforcing jacket surrounding said liner and having an exhaust conduit integral therewith and extending outwardly therefrom for a predetermined distance and terminating in an outer edge, a sleeve within said conduit loosely contiguous with the walls thereof to etect a heat barrier, said sleeve having a radial ange at its outer extremity in gripping relation with the outer edge of said conduit to render said sleeve and conduit integral.

References Cited inthe tile of this patent UNITED STATES PATENTS 1,666,194 Brockway Apr. 17, 1928 2,009,130 Bachle July 23, 1935 2,395,110 Forrest Feb. 19, 1946 2,438,669 Krenzke Mar. 30, 1948 FOREIGN PATENTS 638,964 Germany Nov. 26, 1936 

